Anything could have been better.The Black Order could have been a good set of Final Bosses for Avengers 1.
Loki was a garbage villain though. Made it even worse when Hulk punked his ass. "hey you know that 1 villain that one of the Avengers beat the crap out of in 1 movie? Lets make him the main villain where the guy that owned him joins up with many other powerful people"Loki was the main villain in the first Avengers, effectively acting as a henchman for Thanos.
And there will be many nameless soldiers in JL too.
Loki was a half assed connection. Having actual henchmen to Thanos would have made a ton of sense, and they would have likely referenced him quite a bit.